1. Field of the Invention
This invention relates to molten mass reaction media. More particularly, this invention relates to control of the flow of a molten mass reaction medium through a reaction zone. Specifically, in its most preferred aspect, this invention relates to controlling the flow of a molten mass reaction medium through a reaction zone in co-current relation by means of reactant, product and/or diluent gases which exert a gas-lift effect on the molten mass medium.
2. Description of the Prior Art
The use of a molten mass as a reaction medium has been suggested for numerous types of chemical reactions. For example, see U.S. Pat. Nos. 2,031,987; 2,053,211; 2,055,313; 2,074,529; 2,100,823; 2,334,583; 2,354,355; 2,682,459; 3,081,256; 3,129,165; 3,210,268; 3,252,773; 3,252,774; 3,270,086; 3,309,419; 3,387,941; 3,440,164; 3,449,458; 3,505,018; 3,553,279; 3,567,412; 3,574,543; 3,586,733; 3,619,144; 3,637,895; 3,697,614; 3,708,270; 3,710,737; 3,740,193; 3,745,109; 3,758,673; 3,852,188; 3,862,025; 3,871,992; 3,876,527; 3,916,617; 3,933,127, 3,941,681; 3,948,759 and 4,017,271. Advantages of molten media include effective heat transfer, promotion of uniform contact between reactants, rapid achievement and maintenance of a high reaction zone temperature, promotion of fast reaction times and, in certain instances, the absorption of by-products.
The use of molten mass reaction media is not, however, without difficulties. For example, molten media are difficult to handle and especially to transport. Valves, pumps or other parts of the system which have moving parts in direct contact with the molten mass reaction medium pose particular problems. Even partial solidification of the medium may result in plugging or jamming of such devices. Moreover, constant exposure to the physical and chemical action of the medium may cause rapid deterioration of such devices. A further difficulty arising from the use of a molten mass reaction medium lies in the area of controlling the medium flow. In many instances, it is desirable to be able to control the flow of reaction medium independently of the flow of reactants, products and/or diluents through the system. Due to the high heat capacities and the viscosities of molten reaction media, adjustment of reaction conditions (temperature, reactant/reaction medium proportions, flow rates, etc.) may be difficult.
Flexible control may be achieved by appropriate hydraulic design of the system, but hydraulic flow adjustments are often too slow for proper control of reaction conditions. There is a need for a technique for making rapid molten mass reaction medium flow adjustments in order to achieve optimum process control. In systems where a common molten mass reaction medium is used in a series of successive zones, the medium requirements of successive zones may differ and the requirements of individual zones may fluctuate, thus making it desirable to be able to independently control the flow of the common reaction medium through the different zones.